1. Field of the Invention
The invention relates to a gas-cooled nuclear reactor having a bed of spherical fuel elements, a cavity located in a pressure vessel to house the reactor core and a plurality of steam generators. More particularly, the reactor arrangement provides for the reactor core and the steam generators on two different horizontal planes.
2. Background of the Prior Art
Gas-cooled nuclear reactors having a bed of spherical fuel elements in the so-called cavern design, i.e. wherein the reactor core and the steam generators are installed in the cavity of a prestressed concrete pressure vessel are known in the prior art. The arrangement of the components, namely the reactor core and the steam generators relative to each other, may be effected in a different manner in the various types of reactors.
One gas-cooled nuclear reactor having a bed of spherical fuel elements is known, the THTR-300. In this reactor the steam generators are arranged on a pitch circle around the reactor core. This arrangement places the steam generators at approximately the same height as the reactor core. The blowers required for the circulation of the cooling gas are housed in the side wall of the prestressed concrete pressure vessel. The cooling gas flows from top to bottom through the reactor core.
It is also known to arrange the reactor core and the steam generators on two different horizontal planes so that the steam generators are located in the axial direction underneath the reactor core, see for example British Patent Specification No. 1 025 859. The steam generators (six steam generators are provided in the preferred embodiment of the patent) are placed on a circle at equal angular distances from each other around the axis of the pressure vessel. They are accessible from the bottom of the reactor structure only. The blowers, each of which is connected with one of the steam generators, are installed in the side wall of the pressure vessel, directly below the steam generators. Cooling gas flows from top to bottom through the reactor core.
In a further nuclear reactor installation utilizing the cavity design, the steam generator consisting of a plurality of units is again arranged below the reactor core, see for example West German Offenlegungsschrift No. 15 14 501. A blower is provided for each of the generator units. The blowers, each of which is connected with one of the steam generators, are installed in the side wall of the pressure vessel, in this case, over the steam generator. Cooling gas flows from top to bottom through the reactor core.
In another nuclear reactor installation of the cavity design the steam generator consisting of a plurality of units is again arranged below the reactor core. A blower is provided for each of the steam generator units. The blowers installed in the side wall of the pressure vessel are located directly adjacent to the steam generator units. Cooling gas flows in the horizontal direction through the latter, passing through the reactor core from top to bottom and collecting in a central chamber between the steam generator units. The steam generators in this arrangement are not accessible at all from the outside of the reactor.
It is further known to install each blower directly underneath the steam generator associated with it. A gas-cooled nuclear reactor having the several steam generators located in a plane lower than the reactor core is described in West German Offenlegungsschrift No. 22 16 848. In this arrangement, however, the nuclear reactor is not constructed in a cavity type of layout, but rather comprises a separate, vertically extending space for each steam generator together with its blower in the pressure vessel. All of these spaces are communicating with the principal chamber containing the reactor core. The vertical spaces are distributed uniformly around the axis of the pressure vessel and accessible from the bottom side of the pressure vessel.
The state-of-the-artfinally includes a nuclear reactor with a bed of spherical fuel elements in a cavity type layout wherein the heat generated in the reactor core is again utilized by means of steam generation. This nuclear reactor, sometimes called an AVR, is, however, equipped with one steam generator only, the latter being arranged over the reactor core. The blowers to circulate the cooling gas flowing through the reactor core from bottom to top are located below the reactor core in this nuclear reactor. This known nuclear reactor with a bed of spherical fuel elements has the disadvantage that no extrapolation to reactor type with higher capacities is possible.